Prof Mackay's talk pretty much says that in order to use renewable energy the whole UK would have to be covered in electricity generating equipment.
However, 15% of UK energy is generated from renewables (excluding nuclear), which would mean that currently one seventh of the landmass of the UK was covered in wind turbines etc. Which it isn't. You'd be able to tell.
So, one of us has made a mistake with our calculations somewhere.
To start with, you're talking about electricity generation, where he is talking about total energy requirements. So your 15% figure doesn't include the energy consumption of cars, aeroplanes, many types of heating etc.
I believe he also includes the embodied energy of imports (this was in his book), where if goods are manufactured overseas and imported, it may make sense to count the energy used to manufacture them, depending on what you're measuring exactly.
For example, there's little difference between importing aluminium, or importing energy and bauxite and smelting it yourself.
Also, area use will not increase linearly with the addition of many renewables, because in many cases the best sites are taken first. Hydro can generate a lot of energy around the clock, but you quickly run out of the best locations. Wind strength varies across the country.
In a small country like the UK, solar isn't going to vary much by latitude, and you can probably build it out all over the country. But time shifting of demand isn't always possible, so even if the panels were free, using them to push from (say) 50% of energy from renewables to 100% is going to involve some kind of storage system, which is either going to be very expensive (probably exceeding GDP) and unproven (eg hydrogen fuel cells, lithium ion batteries), or require a ton of space and specific terrain, like pumped water. So that's going to cost a lot of space.
Lastly, electricity isn't always the desired final form. If you're powering jet planes, you're going to need some type of biofuel, which is very inefficient per unit area. If and when hydrogen planes are developed, this will stop being an issue (electric cars have already proven their viability).
I highly recommend his book. It's a brilliant read, he nicely boils down the issues, and is thoroughly committed to stopping global warming - it's not some doom and gloom oil industry sponsored thing. But he doesn't have his head in the sand about how hard a switch to renewables is going to be, unlike (unfortunately) a ton of the green movement seems to.
Ok, if we're talking total energy, then 5% rather than 15%. The point still stands.
I've no idea why he would include imports. Does he exclude exports? It seems a bit mad. There's a huge difference between me buying some aluminium and having to generate the electricity at my home to smelt it myself as a kind of cottage industry! (A case of he who smelted, dealt it?)
The point about area use not increasing linearly is a good one. However, Prof Mackay doesn't do this. He consistently states that - even giving renewables every advantage and pretending they'll always work at peak efficiency - you'd still have to blanket the country with them to make them effective.
I've read his book and it's where I first started to think there was something a bit off in what he was saying. Yes, he's very full of the idea that he's the hard-nosed realist and anyone who disagree must have their heads in the sand. I've heard that tactic before.
If your goal is sustainability, there is no difference. Pushing your energy consumption out to another country is just shifting the problem. Though yes, you would want to exclude exports in this model.
Picture a hypothetical country that solely consists of stay at home programmers making large sums of money, powered entirely by solar, but importing vast amounts of physical goods manufactured in environmentally unfriendly ways. The country would by traditional measures be a perfect model of sustainability, but it is simply paying others to do unsustainable actions on its behalf.
The book isn't really "saying" much, for the most part. The vast bulk of it is simple, back of the envelope calculations for energy consumption which shows working. I realize you might not want to take a half hour to find specific faults in it, but it is not helpful say there is "something a bit off" with a work like that, when the source code is published for all to see.
For instance, that he counts embodied energy of imports, and you do not wish to, makes a big difference to the bottom line. Just skimming the chapter headings is enough to point out a concrete disagreement.
Fair point about the hard nosed realist tactic often being used to discredit dissenting views. That wasn't my intention, I was more trying to say that the conclusions presented should not be used to infer some political position of the author.
There are a ton of studies paid for by the oil industry that paint all kinds of pictures, I just meant it's not a book like that. If I realized you'd already read it, I wouldn't have included that part.
Having read the book the specific fault with it is that the results it comes up with from its simple back of the envelope calculations, bear no resemblance to actual reality and are therefore wrong.
Including imports is wrong. In your hypothetical country, fixing those unsustainable actions is up to the country they're importing goods from. Show that they can't use wind/solar on their landmass if you want. The idea that every area of a country (or indeed the world) are equally good at generating power is obviously incorrect. Claiming that this makes wind and solar power unusable is equally incorrect.
The book reads like it was paid for by the nuclear industry (I don't think it was; it just reads that way).
If your talking total energy then you need to include food and farms already take a lot of land.
So, while close it's vary misleading as going 100% renewable would take less new land than he is suggesting. Add to that you can mix wind farms and regular farms at the cost of less than 1% of the farm land. Not to mention off shore wind farms. Which further reduces the land requirements well below his calculations.
Also, Hydro is vary efficient built in storage using it 24/7 is vary wasteful.
Wind is 24/7, and solar aligns with peak demand fairly well. Anyway, rather than storage your better off with extra wind capacity that's often wasted, with solar to meet your daily peak and hydro to fill in the gaps.
PS: Adding a few peaking power plants is still a good idea, going 80% renewable is a much more reasonable goal until most of the world is at that point. It's silly to chase a few extra % when china is using so much coal power.
According to [1] in 2012 for the UK renewables provided 11.3% of electricity demand and 3.94% of total energy demand. It's an important distinction, because petrol natural gas and jet fuel aren't renewable.
MacKay is the author of a book - "Sustainable Energy without the hot air" - which lays out all his calculations and the rationales behind the inputs. And it's available online [2]. So if you want to audit his calculations, have at it!
I've looked at the book, there's when I checked his figures and they seemed to disagree with reality.
So, electricity is about 1/3 of total energy. The 15% figure is the latest one for the last quarter of 2013[1] (PDF, see page 13). That means that (according to Prof Mackay) 5% of the UK is covered in renewable electricity generation.
> However, 15% of UK energy is generated from renewables (excluding nuclear), which would mean that currently one seventh of the landmass of the UK was covered in wind turbines etc. Which it isn't.
Most likely brought in from other countries, and the wind parks in the North Sea.
Many local utilities in Germany hold stakes e.g. in a Norwegian (iirc) dam project, so they recieve a given amount of electricity output. This increases Germany's renewable-source amount even if the energy itself isn't produced in Germany.
Nope, Scotland over produces and sells to England, but that's still UK, at least for another month ;-)
Offshore wind was included in the impossible. There's something off in his figures. Perhaps wind turbines have become more efficient since he first made his calculations?
It may also be diminishing returns, not all land is equal for wind turbine placement. If all the "good" spots can't generate enough for the UK's needs you might need to start using less suitable locations.
By far the most efficient wind turbine placements are offshore. We have plenty of coast, and so far very little of it has offshore wind farms.
We also have a good few estuaries that could create electricity relatively easily - using known and proven technology, which fusion certainly isn't.
Bottom line is these figures are either incompetent or disingenuous.
I'm old enough to remember fusion being touted as the Next Big Thing for literally all of my life. Commercial containment fusion seems no closer now than it did fifty years ago.
There are alternatives, but they're highly speculative. Dropping YC cash on them makes sense as a long shot, but the science doesn't suggest it's wise to expect them to make good.
However, 15% of UK energy is generated from renewables (excluding nuclear), which would mean that currently one seventh of the landmass of the UK was covered in wind turbines etc. Which it isn't. You'd be able to tell.
So, one of us has made a mistake with our calculations somewhere.